From: "Peter Zijlstra (Intel)" <pet...@infradead.org>
Provide static calls to control cond_resched() (called in !CONFIG_PREEMPT)
and might_resched() (called in CONFIG_PREEMPT_VOLUNTARY) to that we
can override their behaviour when preempt= is overriden.
Since the default behaviour is full preemption, both their calls are
ignored when preempt= isn't passed.
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Mel Gorman <mgor...@suse.de>
Cc: Ingo Molnar <mi...@redhat.com>
Cc: Michal Hocko <mho...@kernel.org>
Cc: Paul E. McKenney <paul...@kernel.org>
[branch might_resched() directly to __cond_resched(), only define static
calls when PREEMPT_DYNAMIC]
Signed-off-by: Frederic Weisbecker <frede...@kernel.org>
---
include/linux/kernel.h | 22 +++++++++++++++++++---
include/linux/sched.h | 27 ++++++++++++++++++++++++---
kernel/sched/core.c | 16 +++++++++++++---
3 files changed, 56 insertions(+), 9 deletions(-)
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 2f05e9128201..ecd820174455 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -15,6 +15,7 @@
#include <linux/typecheck.h>
#include <linux/printk.h>
#include <linux/build_bug.h>
+#include <linux/static_call_types.h>
#include <asm/byteorder.h>
#include <asm/div64.h>
#include <uapi/linux/kernel.h>
@@ -194,11 +195,26 @@ struct pt_regs;
struct user;
#ifdef CONFIG_PREEMPT_VOLUNTARY
-extern int _cond_resched(void);
-# define might_resched() _cond_resched()
+
+extern int __cond_resched(void);
+# define might_resched() __cond_resched()
+
+#elif defined(CONFIG_PREEMPT_DYNAMIC)
+
+extern int __cond_resched(void);
+
+DECLARE_STATIC_CALL(might_resched, __static_call_return0);
+
+static __always_inline void might_resched(void)
+{
+ static_call(might_resched)();
+}
+
#else
+
# define might_resched() do { } while (0)
-#endif
+
+#endif /* CONFIG_PREEMPT_* */
#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
extern void ___might_sleep(const char *file, int line, int preempt_offset);
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 063cd120b459..f1d6f274e0dc 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1829,11 +1829,32 @@ static inline int test_tsk_need_resched(struct
task_struct *tsk)
* value indicates whether a reschedule was done in fact.
* cond_resched_lock() will drop the spinlock before scheduling,
*/
-#ifndef CONFIG_PREEMPTION
-extern int _cond_resched(void);
+#if !defined(CONFIG_PREEMPTION) || defined(CONFIG_PREEMPT_DYNAMIC)
+extern int __cond_resched(void);
+
+#ifdef CONFIG_PREEMPT_DYNAMIC
+
+DECLARE_STATIC_CALL(cond_resched, __static_call_return0);
+
+static __always_inline int _cond_resched(void)
+{
+ return static_call(cond_resched)();
+}
+
#else
+
+static inline int _cond_resched(void)
+{
+ return __cond_resched();
+}
+
+#endif /* CONFIG_PREEMPT_DYNAMIC */
+
+#else
+
static inline int _cond_resched(void) { return 0; }
-#endif
+
+#endif /* !defined(CONFIG_PREEMPTION) || defined(CONFIG_PREEMPT_DYNAMIC) */
#define cond_resched() ({ \
___might_sleep(__FILE__, __LINE__, 0); \
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index d2003a7d5ab5..6432d0079510 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6111,17 +6111,27 @@ SYSCALL_DEFINE0(sched_yield)
return 0;
}
-#ifndef CONFIG_PREEMPTION
-int __sched _cond_resched(void)
+#if !defined(CONFIG_PREEMPTION) || defined(CONFIG_PREEMPT_DYNAMIC)
+int __sched __cond_resched(void)
{
if (should_resched(0)) {
preempt_schedule_common();
return 1;
}
+#ifndef CONFIG_PREEMPT_RCU
rcu_all_qs();
+#endif
return 0;
}
-EXPORT_SYMBOL(_cond_resched);
+EXPORT_SYMBOL(__cond_resched);
+#endif
+
+#ifdef CONFIG_PREEMPT_DYNAMIC
+DEFINE_STATIC_CALL(cond_resched, __static_call_return0);
+EXPORT_STATIC_CALL(cond_resched);
+
+DEFINE_STATIC_CALL(might_resched, __static_call_return0);
+EXPORT_STATIC_CALL(might_resched);
#endif
/*
--
2.25.1
